Black British women in Hackney, East London, are diagnosed with breast cancer 21 years younger than white British women, according to a Cancer Research UK study published online in the British Journal of Cancer.

In the first UK study to look at the patterns of breast cancer in black British women, the researchers studied 102 black women and 191 white women diagnosed with breast cancer at Homerton University Hospital in Hackney, East London, between 1994 and 2005. They found the black patients were diagnosed with breast cancer at an average age of 46 while the white patients were diagnosed at an average age of 67.

Researchers based at the Institute of Cancer and Cancer Research UK clinical centre at Barts and the London School of Medicine and Dentistry also found that survival was poorer among black women with smaller tumours. In addition, their initial findings suggest that tumours in the younger black patients were more likely to be aggressive, and a higher proportion of tumours were basal-like  meaning they were less likely to respond to newer types of targeted breast cancer treatments like Herceptin.

If these results are confirmed in larger studies, the findings could have implications for diagnosis, screening and treatment of black British breast cancer patients in the future.

Study author Dr Rebecca Bowen, said: "Twenty five per cent of all breast cancer cases diagnosed in London during the period studied were in women aged 45 or younger  but this figure rose to 45 per cent among the black population in Hackney. We think the differences in the way tumours of black and white women behave can be put down to the biological differences between the two ethnic groups. We're now trying to find out why the tumours are so different so that we can develop new treatments to target the aggressive forms of breast cancer seen in young black women."

Until recently, UK cancer registries have not collected ethnicity data routinely, but incidence of breast cancer among black British women is thought to be lower than the white population. American research has suggested that African-American women get breast cancer at a younger age and at a more advanced stage  but this is the first UK study to draw these conclusions.

Dr Bowen added: "We've just received funding for the next stage of our research which will allow us to determine the type of cancers these women are getting at this young age. It's important that we use the information learnt from this study to raise awareness of breast cancer risk factors and the importance of early detection among the black population."

Dr Lesley Walker, Cancer Research UK's director of cancer information, said: "This is very interesting research. The fact that black women are being diagnosed with breast cancer at a much younger age than white women is clearly worrying. If these results are confirmed in follow-up studies, it might be appropriate to alter screening services offered to black women to better reflect the age at which they are diagnosed with breast cancer  but at the moment its too early to suggest any changes to the screening programme because the study was so small.

"These findings highlight the need for all women to be breast aware, report any changes to the doctor promptly and attend screening appointments when invited, as early detection is important for successful treatment."